Top seed Rafael Nadal says he is vulnerable to losing against rising British star Jack Draper in the Australian Open first round.

Spain's Nadal, the defending men's champion, has lost six of his past seven matches, a run stretching back to last year's US Open.

Draper, 21, has emerged as one of the tour's hottest prospects and reached the Adelaide semi-finals this week.

"He is one of the toughest first-round opponents possible," said Nadal, 36.

"He is young, powerful, growing very fast and playing well."

Asked if he felt vulnerable going into Monday's opening match, he added: "Yes, without a doubt. I have been losing more than usual, so that's part of the business."

Nadal won the Australian Open title last year, a few months after facing concerns that a foot injury might force him to retire.

Another major victory followed at the French Open - the tournament he has won 14 times - taking him to 22 Grand Slam titles and clear of long-time rivals Roger Federer and Novak Djokovic.

The Mallorcan left-hander played through Roland Garros with chronic foot pain and then withdrew from his Wimbledon semi-final against Nick Kyrgios with a torn abdominal muscle.

While he returned to play the US Open and reached the fourth round, Nadal has struggled to pick up many victories since.

The world number two, who is the top seed in Melbourne after Spanish teenager Carlos Alcaraz withdrew injured, has started the 2023 season with defeats by British number one Cameron Norrie and Australia's Alex de Minaur at the United Cup.

"I need to build again all this momentum. I need to build again this confidence with myself with victories," said Nadal.

"By the way, I didn't play that bad in the first two matches the year. I lost against two great opponents but having very positive chances to win both matches.

"I feel ready, honestly. The only thing that didn't happen for me is victories."

Draper is making his Australian Open debut, having climbed from outside the world's top 250 into the top 40 in the past year.

The left-hander, who earned victories over top-10 opponents Stefanos Tsitsipas and Felix Auger-Aliassime in August, says he has the belief he can cause a shock against his idol Nadal.

"I want to go out there and fight hard for every ball and I honestly believe that my tennis is good enough to beat a lot of guys; I feel confident," he said.

"I sometimes have to remind myself that I've only been on tour for six months now. So I'm still gaining a lot of experience but I can feel confident in my tennis."

Murray not worried by tough draw

British former world number one Andy Murray says he feels "ready to play a top player early on" after being drawn against 13th seed Matteo Berrettini in Melbourne.

The 35-year-old Scot lost to Italy's Berrettini - the 2021 Wimbledon runner-up and a Melbourne semi-finalist last year - in the US Open third round.

"It's obviously a tough draw. But I also feel like I'm in a much better place than where I was during any of the Slams last year coming into it," said 49th-ranked Murray, a five-time runner-up at Melbourne Park.

"I feel well prepared. I feel ready to play a top player early in the event.

"Maybe last year, at times, my game didn't feel that great and getting a difficult draw, a tough match early in the tournament, didn't felt great."